Post-exertion restitution of left ventricular systolic time intervals in healthy subjects

The left ventricular systolic function was studied in 123 healthy men aged 23-24 years under the influence of exercise and during a two-hour restitution period. Left ventricular systolic time intervals (LVSTI) were evaluated by means of the Blumberger method with Holldack's modification before the exercise, immediately after its termination and after 30, 60 and 120 minutes. After exercise, a decrease was found in the absolute values of LVSTI and of the diastolic stage. During two-hour restitution, the authors found a decrease of left ventricular ejection time, total mechanical systolic time, total electromechanical systolic time, total ventricular electrical stimulation time and of the diastolic stage. A statistically highly significant decrease of all mentioned intervals was related to persisting, still after 2 hours, increased heart rate with which these intervals significantly correlated. The share (in percent) of LVSTI in the total cardiac cycle increased after exercise and was still increased after 2 hours following its termination. The relative increase of systolic time intervals was accompanied by a decrease in the duration of the diastolic stage.